Poultry litter is primarily disposed of through land application. This traditional approach creates problems with odor, transportation costs and does not harness the energy potential of the waste stream at the farm. Increasingly, risks of over-application and surface water contamination have been highlighted. For example, in South Carolina, there are an estimated 181 permitted turkey facilities and 556 poultry facilities producing an estimated combined 692,414 tons of poultry litter.
Most states have adopted tougher water quality and environmental regulations that restrict and limit the amount of poultry litter that can be land applied based on the amount of nutrients required for crops and soil conditions. These actions, while environmentally sound, limit the amount of manure solids (i.e., poultry litter) that farmers may apply to their land, which imposes an economic burden on the farmer. Further, the composition of the waste varies significantly from location to location and with different types of agricultural operations being performed.
Other methods have been developed to dispose of animal waste by burning and land applying the ash. The energy value of poultry litter is approximately 3,500 BTU/lb. Thus, poultry litter represents a form of biomass with enormous potential as a source of renewable energy. Capitalizing on the large amount of untapped energy source in poultry litter could potentially displace a portion of the country's dependence on imported fossil fuels. However, prior art methods and systems require high temperatures to reduce the waste to ash by combustion. Although, the volume of animal waste is reduced by transforming the waste to ash, such prior art systems are inefficient and are not capable of providing multiple forms of energy from processing animal waste in an environmentally friendly manner.
Accordingly, what is needed in the art is an improved method and system for processing animal waste that has increased efficiency and also has an ability to provide multiple forms of energy.